We started Morrie when he was six months old in agility classes. So far he has jumped 22" ONCE (by accident), which is where he will end up jumping when he is the correct age, by height default. We usually jump 10" and not very much since he is still only 10 months old.
We were at our first trial this past weekend (to watch and volunteer since our club was hosting it and AgilityPup was working on her junior handler's title!), and saw a LOT of border collies and dude, were they ever FAST. We watched one in particular who was very very good, circle his owner all the way til the start line and then occasionally in between obstacles, lol, he would get so excited that he would circle again. They seem to do really really well with it if you can focus.
They do recommend obedience classes, but ours didn't. AgilityPup's dog, Zoey had only been on a leash half a dozen times before we started our classes. We had absolutely no idea what we were getting into but our dogs have stayed on track with the rest of the class (several of whom are obedience class graduates!), with a little bit of extra elbow grease. Your basic commands - come, sit, stay, down, and heeling are very good to have - Morrie only knew how to sit and heel as he was shown conformation before we got him!
I do also recommend classes - there were plenty of things we worked on, especially in our foundations class, to help them focus and stay with you that I would never have thought of and it does just that, builds a very good foundation with your dog so you can trust them off leash and work with them easily without them getting distracted.